In a turbomachine, such as a gas turbine engine, air is pressurized in a compressor section then mixed with fuel and burned in a combustor section to generate hot combustion gases. The hot combustion gases are expanded within a turbine section of the engine where energy is extracted to power the compressor section and to produce useful work, such as turning a generator to produce electricity. The hot combustion gases travel through a series of turbine stages within the turbine section. A turbine stage may include a row of stationary airfoils, i.e., vanes, followed by a row of rotating airfoils, i.e., turbine blades, where the turbine blades extract energy from the hot combustion gases for powering the compressor section and providing output power. Since the airfoils, i.e., vanes and turbine blades, are directly exposed to the hot combustion gases, they are typically provided with internal cooling channels that feed a cooling fluid, such as compressor bleed air, through the airfoil and through various film cooling holes around the surface thereof.
One type of airfoil extends from a radially inner platform at a root end to a radially outer portion of the airfoil, and includes opposite pressure and suction sidewalls extending axially from leading to trailing edges of the airfoil. The cooling channel extends inside the airfoil between the pressure and suction sidewalls.
After periods of use, it has been found that areas adjacent to locations near the airfoil leading edges where the airfoils intersect with the platform lacks adequate cooling. Therefore, these areas are susceptible to damage, i.e., due to overheating and oxidation, such that repair/replacement procedures are required.